1. Technical Field
The present invention relates to solar cells, and particularly, to a solar cell made of semi-conductive compounds.
2. Description of Related Art
Currently, various solar cells have been designed to receive and convert sunlight into electrical energy. Such solar cells have been applied on roofs of buildings and cars, or applied on portable electronic devices.
In a typical solar cell, a P-type semiconductor layer and an N-type semiconductor layer are two key components. When sunlight projects on surfaces of the P-type semiconductor layer or the N-type semiconductor layer, a part of the sunlight is unavoidably reflected by the surfaces, and the other is absorbed. Photons in the absorbed sunlight collide with electrons in the P-type semiconductor layer or the N-type semiconductor layer, thereby, electron-hole pairs are generated, and thus an electric field is formed between the P-type semiconductor layer and the N-type semiconductor layer, i.e., a photon-electron conversion is realized.
The P-type semiconductor layer and N-type semiconductor layer of the solar cell can be made of silicon based materials, or semi-conductive compounds. However, cost of the silicon based materials is hard to be reduced. In addition, lattice defects, such as dislocations and stacking faults, are prone to occur in the semiconductor layers during formation when the semi-conductive compounds are used, and thus the efficiency of the photon-electron conversion is difficult to be improved.
What is needed, therefore, is a solar cell with fewer lattice defects and higher photon-electron conversion efficiency using the semi-conductive compounds.